1. Field of the Invention
The present invention relates to a process for producing a semiconductor device, and more particularly to a process whereby a resin-sealed semiconductor device having high reliability can be efficiently produced without voids.
2. Brief Description of the Prior Art
It is common practice to seal a semiconductor device with a resin to protect a circuit surface. Such resin-sealed semiconductor devices are generally manufactured by mounting individual IC chips on respective chip mounting substrates and sealing each chip with a resin using a mold.
More specifically, currently employed methods are:
(1) IC chip is connected with a chip mounting substrate through a gold wire or the like, and is sealed with a resin.
(2) IC chip is mounted on a chip mounting substrate having conductive protrusions and is connected with the substrate via the conduction protrusions, and is thereafter sealed with a resin.
(3) IC chip is connected with a chip mounting substrate through an anisotropic conductive film or paste, and is thereafter sealed with a resin.
In the method (1) given above, the sealing resin has to be molded in a size enough to encapsulate the gold wire as well, and consequently the semiconductor device has a size far larger than the chip size. Therefore, this method is unsuitable for small apparatuses such as cellular phones. Accordingly, the methods (2) and (3) are more used because they can produce semiconductor devices as small as the chip size.
However, the method (2) causes spacing between the IC chip and the chip mounting substrate by the height of the conductive protrusions. The sealing resin cannot fill the spacing adequately and voids often result. Accordingly, prior to the resin sealing, an insulating resin (underfill resin) must be filled between the IC chip and the chip mounting substrate.
The method (3) requires troublesome work in applying an anisotropic conductive film or paste to a small IC chip. Particularly, it is difficult to apply the anisotropic conductive paste in a constant amount. When the paste is used in amounts differing in each application, device properties could be nonuniform.
To solve such problems, JP-A-2001-144140 discloses a method for producing a semiconductor device comprising providing a semiconductor wafer having circuits on a surface, forming an adhesive thin layer on the circuit surface of the semiconductor wafer, cutting the semiconductor wafer into chips by each circuit, mounting each chip on a predetermined position of a chip mounting substrate through the adhesive thin layer, and firmly bonding the chip on the chip mounting substrate so as to form conduction between the chip and the chip mounting substrate.
The method described above produces chips by dicing a semiconductor wafer that has an adhesive thin layer on its circuit surface. Because the chips obtained have the adhesive thin layer adhered on the circuit surface thereof, voids can be prevented in the resin sealing and products having high uniformity and reliability may be obtained.
However, this method requires application of a dicing tape to the back of the semiconductor wafer in order to fix the wafer during cutting into chips (Paragraph [0030] of JP-A-2001-144140).
The present invention has been made in view of the background art as described above. Therefore, it is an object of the invention to provide a process whereby a resin-sealed semiconductor device having high reliability may be produced more easily and efficiently without formation of voids in mold resin.